1. Thiaminase I: Thiaminase-I is involved in the degradation of thiamin (vitamin B1). The structure of Thiaminase-I has been determined by MIR methods with data collected on a rotating anode(Res=2.6Angst). Higher resolution native data were collected at CHESS beamline A1 for structure refinements. The CHESS data are summarized below: Nov. 11, 1994 CHESS A1, 1kx1k CCD Feb. 17, 1995 2kx2k CCD Space Group: P21212 Space Group P21212 a=85.7; b=117.5; c=36.57 a=86.6; b=119.4; c=37.0 Res=2.0 Res=1.6Angst completeness= 90% Completeness= 80% Rmerge=6.0 Rmerge=7.0 usable for refinement Not usable due to ice rings and systematic incompleteness 2. THIK: ThiK is a thiazole kinase that is 272 Amino acids long (+12 other amino acids for polyHis expression). There are 4 Met's within the protein sequence.Native data along with a HG derivative were collected at CHESS A1 on the ADSC CCD detector in April, 1996: lamda=0.914 Angst. Native:(R3;a=b=77.5A, c=230.40; Rmerge=6%; completeness=96%, Res=1.6A) Hg derivative:(R3;a=b=77.5A, c=230.40; Rmerge=7.3%; completeness=99%, Res=2.5A) We are currently attempting to solve the structure via SIR. In parallel,crystallization of Se-Met ThiK is currently underway. Once crystals are produced, MAD data will be collected on beamline F2. This project will allow for the further development of the MAD station at CHESS. We will be able to test for the measurability of the expected weak Se-anomalous signal. If difficulty arises, the SIR data will aid the phasing. 3. ThiC: ThiC is the coupling enzyme; it is 23KD and contains 7 Met's. Pyrimidine and thiazole are coupled together to form thiamine. Native data were collected at CHESS beamline A1 with ADSC CCD detector in May, 1996. The Laue Group is 4/mmm w/ a=b=78 c=142. The space group is P41212 or P43212 Rmerge=5.4, completeness=87%, res=2.2A. Crystallization of the Se-met ThiC protein are underway. This is also a project to aid the development of the MAD beamline. The large number of Se's adds to the difficulty of the project. Few proteins with as many Se's have been solely phased by MAD.